Multi-modal maximum power point tracking optimization solar photovoltaic system

ABSTRACT

A maximum power point tracking optimizer is connected to and powered by at least one solar cell. The maximum power point tracking optimizer configured to operate: in a pass-through mode when said at least one solar cell voltage is greater than a passthrough threshold and greater than a ratio of the open-circuit voltage of said at least one solar cell, said pass-through mode flowing current through a pass-through circuit; in an optimizing mode when said at least one solar cell voltage is greater than an optimizing threshold and less than a ratio of the open-circuit voltage of said at least one solar cell, said optimizing mode modulating current flow using a DC-to-DC switching circuit to direct the voltage of said at least solar cell towards said ratio of the open-circuit voltage; in an active bypass mode when said at least one solar cell voltage is less than an active bypass threshold, said active bypass mode flowing current through an active bypass circuit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase patent application of PCT/US2016/063209, filed Nov. 21, 2016, which claims priority to U.S. provisional patent application 62/257,698 filed on Nov. 19, 2015, both of which are hereby incorporated by reference in the present disclosure in their entirety.

FIELD OF THE INVENTION

The present disclosure relates in general to the fields of solar photovoltaics (PV), and more particularly to maximum power point tracking and solar photovoltaic systems.

BACKGROUND

As solar photovoltaic (PV) cells and solar PV systems become more widespread, these technologies will increasingly benefit from improved power harvesting. Solar PV installations are installed in a wide variety locations and thus subject to varying changes in sunlight, shading, and temperature all of which impact solar PV cell power generation. These varying changes may impact the power generation of solar PV cells electrically connected in the same solar PV system differently. Additionally, solar PV cells connected in the same module, panel, or string, may have power generation variances under the same conditions, even when the cells were fabricated alike, due to inherent solar cell structural variances. Solar PV cell failures and electrical connection failures also contribute to power generation variances. Solar PV cell power generation variances often hampers and reduces solar PV cell and solar PV system power harvesting.

BRIEF SUMMARY OF THE INVENTION

Therefore, a need has arisen for a maximum power point tracking optimization solar photovoltaic system providing improved power harvesting. In accordance with the disclosed subject matter, a multi-modal maximum power point tracking optimization solar photovoltaic systems are provided which may substantially eliminate or reduces disadvantage and deficiencies associated with previously developed maximum power point tracking optimization solar photovoltaic systems.

According to one aspect of the disclosed subject matter, a multi-modal maximum power point tracking optimization solar photovoltaic system is provided. A maximum power point tracking optimizer is connected to and powered by at least one solar cell. The maximum power point tracking optimizer configured to operate: in a pass-through mode when said at least one solar cell voltage is greater than a pass-through threshold and greater than a ratio of the open-circuit voltage of said at least one solar cell, said pass-through mode flowing current through a pass-through circuit; in an optimizing mode when said at least one solar cell voltage is greater than an optimizing threshold and less than a ratio of the open-circuit voltage of said at least one solar cell, said optimizing mode modulating current flow using a DC-to-DC switching circuit to direct the voltage of said at least solar cell towards said ratio of the open-circuit voltage; in an active bypass mode when said at least one solar cell voltage is less than an active bypass threshold, said active bypass mode flowing current through an active bypass circuit.

The photovoltaic system comprises a photovoltaic module attached to a photovoltaic mount frame, the mount frame having a rectangular shape. A deflector is attached to the mount frame by a rotatable deflector and mount frame attachment wherein the deflector pivots around the rotatable deflector and mount frame attachment from a nesting position under the photovoltaic module in the mount frame to an installation position raising at least a first side of the mount frame. A mount foot is attached to the deflector by a rotatable mount foot and deflector attachment wherein the mount foot pivots around the rotatable mount foot and deflector attachment from a nesting position in a mount foot nesting indention in the deflector to an installation position planar to a mounting surface.

These and other aspects of the disclosed subject matter, as well as additional novel features, will be apparent from the description provided herein. The intent of this summary is not to be a comprehensive description of the claimed subject matter, but rather to provide a short overview of some of the subject matter's functionality. Other systems, methods, features and advantages here provided will become apparent to one with skill in the art upon examination of the following FIGUREs and detailed description. It is intended that all such additional systems, methods, features and advantages that are included within this description, be within the scope of any claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, natures, and advantages of the disclosed subject matter may become more apparent from the detailed description set forth below when taken in conjunction with the drawings (dimensions, relative or otherwise not drawn to scale) in which like reference numerals indicate like features and wherein:

FIG. 1 is a diagram showing a distributed maximum-power-point tracking (MPPT) power optimization solar photovoltaic system in accordance with the disclosed subject matter;

FIG. 2 is a functional block diagram of an exemplary multi-modal MPPT power optimizer;

FIG. 3 shows a representative timing diagram for a sample and hold (S&H) circuit;

FIG. 4 is a flow chart of multi-modal MPPT operation;

FIG. 5 is a power vs. voltage graph;

FIG. 6A is a functional block diagram and FIGS. 6B and 6C and 6D are expanded views of FIG. 6A; and

FIG. 7 is a table showing an MPPT optimizer consistent with FIG. 6A in different modes.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense, but is made for the purpose of describing the general principles of the present disclosure. The scope of the present disclosure should be determined with reference to the claims. Exemplary embodiments of the present disclosure are illustrated in the drawings, like aspects and identifiers being used to refer to like and corresponding parts of the various drawings.

And although the present disclosure is described with reference to specific embodiments, fabrication and installation processes, and materials, one skilled in the art could apply the principles discussed herein to other electronic components, solar photovoltaic systems comprising combinations of solar cells, electronic components such as integrated circuits (IC) and IC packages, fabrication and installation processes, as well as alternative technical areas and/or embodiments without undue experimentation. Solar PV cells are described with reference to crystalline silicon solar cells, however the solar cells may be thin-film solar cells or alternative solar PV cell structures.

The comprehensive solar photovoltaic (PV) system multi-modal maximum-power-point tracking (MPPT) power optimization solution provided advantageously allows for improved distributed solar PV cell and module power harvesting and maximum-power-point tracking power optimization with increased operational efficiency, enhanced power & energy harvesting, and substantially reduced failure points. Particularly, the solar PV system multi-modal maximum-power-point tracking optimization solution disclosed and described here provides for improved power harvesting of an individual solar cell or combination of electrically connected solar cells for distributed maximum-power-point tracking power optimization at a relatively low power generation level of the system (e.g., including but not limited to that generating a voltage in the range of about 4.5V to 10.5V) and optimizes the power harvesting and reduces the system drain (or power dissipation) of that corresponding solar cell or combination of electrically connected solar cells, relatively autonomously and independently of other electrically connected solar cells (e.g., other electrically connected solar cells in the same string of the solar cell, and/or combination of various solar cells in a photovoltaic module laminate, being optimized).

Structural and functional innovation such as but not limited to system level design, multi-modal MPPT structure and optimization algorithm modes, and current averaging/smoothing through parasitic inductance of connection wirings result in reduced MPPT insertion loss and smooth power adjusting and regulation to provide efficient and effective autonomous self-powered power optimization at a lower system power generation level (for distributed MPPT power optimization localized to the lower system power generation level).

The distributed multi-modal maximum-power-point tracking (MPPT) power optimization solution provided is particularly designed for and advantageously used as an embedded and distributed MPPT solution with reduced electronic failure points (and excellent long-term operational reliability) and improved tracking accuracy and operational efficiency for enhanced and fail-safe power harvesting under a wide range of operating conditions (over a wide range of sunlight irradiance amounts, ambient temperature values, etc.). These solutions are described with reference to distributed solar cell (or solar cell string) MPPT power optimizer integrated circuit (IC) package for regulating the output voltage of a solar cell (or a string of electrically connected solar cells) to its optimum power by regulating the MPPT IC input voltage (e.g., using an electronic circuit voltage regulator), which is the same as the output voltage of a solar cell (or a string of electrically connected solar cells), if and when needed, to a predetermined voltage based on the operating condition of the solar cells. Optimum solar cell (or a string of electrically connected solar cells) voltage is derived by periodically or intermittently measuring the solar cell (or a string of electrically connected solar cells) open circuit voltage (V_(OC)) and then regulating the solar cell (or a string of electrically connected solar cells) voltage to a voltage value corresponding to the product of this open circuit solar cell (or a string of electrically connected solar cells) voltage by a predetermined fixed constant (being between 0.60 and 0.90, and preferably between 0.7 and 0.85; such constant being preferably between 0.75 and 0.80 for crystalline silicon solar cells), if needed. The integrated circuit is preferably silicon based but may alternatively be made using other semiconductor materials such as silicon carbide.

Advantageously for reduced system impact (e.g., module material thermal impact of electronic components) and reduced system cost, among other advantages, the distributed MPPT power optimization solution may be packaged fully or partially as an integrated circuit (IC) and particularly as a low profile (i.e., low package thickness of less than 2 mm, preferably less than 1 mm or 0.6 mm) integrated circuit (e.g., having an operating temperature in the range of −40° C. to +105° C.) for embedding within solar PV module encapsulant materials (e.g., glass, polymeric, and laminate materials). The MPPT IC described in detail is designed to run with incoming solar irradiance as low as about one W/m² (1 watt per square meter) or more (light irradiance received at the solar cell or string of electrically connected solar cells). In other words, as long as the solar cell (or a string of electrically connected solar cells) is generating power with the slightest amount of light (e.g., sunlight) the MPPT IC will be powered up and continue to operate down to the level of about 1 W/m² (corresponding to ˜ 1/1000 of standard test conditions or STC irradiance of 1 kW/m² for solar cell power generation). The exemplary distributed MPPT IC described is a 2.5 amp IC which may operate on and be powered by a supply voltage (solar cell or a string of connected solar cells input differential voltage range of positive voltage V_(P) and negative voltage V_(M)) in the range of about 4.5V to 10.5V (this voltage range may be larger or smaller depending on the system requirements, for example less than 18 volts or in the range of 3 to 15 volts). Thus, the MPPT IC is directly powered by the source it is regulating (e.g., an individual solar cell or combination of solar cells connected in a string of solar cells connected to the MPPT IC input), eliminating the need for a separate power supply. The MPPT innovations described provide for, and the exemplary MPPT IC described, a single layer metal IC package for reduced cost and also reduced coefficient of thermal impact.

MPPT IC may have an efficiency as high as 99.5% or higher (or an insertion loss of less than about 0.5%) in the so-called pass-through mode of operation (pass-through mode is a non-switching mode of operation). The high-side and low-side field-effect transistor (FET) switches (M1 and M2) described provide low Rdson (on resistance between source and drain of FET) resulting in improved MPPT IC operational efficiency. The low-side field-effect transistor or FET (M2) advantageously has slightly more on resistance to make the high side FET (M1) more efficient (less ohmic losses), particularly with single layer metal circuits. The MPPT IC may advantageously have an analog-to-digital converter (ADC) based architecture for sample-and-hold (S&H) function to minimize power consumption and to support relatively long sample and hold times as needed. M1 may have an on-state drain-to-source resistance (Rdson) of less than 50 milli-ohms for the pass-through mode of operation, and more advantageously an on-state drain-to-source resistance of less 25 milli-ohms for the pass-through mode of operation. M2 may have an on-state drain-to-source resistance (Rdson) of less than 100 milli-ohms for the active bypass mode of operation, and more advantageously an on-state drain-to-source resistance of less 60 milli-ohms for the active bypass mode of operation. Additionally, the MPPT IC may have a center exposed metallic pad electrically connected to the negative input and negative output of the MPPT IC for heat sinking.

FIG. 1 is a diagram showing the connections and select functional elements and electrical terminals of a distributed maximum-power-point tracking (MPPT) power optimization solar photovoltaic system in accordance with the disclosed subject matter. Each solar cell (or a string of electrically connected solar cells 2, 4, to m) is electrically connected to an MPPT power optimizer of an MPPT integrated circuit (IC) package (MPPT package 6, 8, to n) and associated components (e.g., capacitors and rectifiers). Associated electrical components may include electrical connection wiring and electronic components such as capacitors, diodes and rectifiers such as Schottky barrier rectifiers (SBRs). The MPPT IC may be attached to a printed-circuit board, and also may be attached in combination with a capacitor C_(IN) and Schottky barrier rectifier 26 to a printed-circuit board, such that the printed-circuit board provides positive and negative input and output leads. Solar cells (or strings of electrically connected solar cells) 2, 4, to m each power up a corresponding MPPT power optimizer having an MPPT integrated circuit (IC) package and associated components. Solar cells (or strings of electrically connected solar cells) 2, 4, to m may be a single solar cell or a combination of electrically connected solar cells forming a string of electrically connected solar cells (e.g., series connected string of solar cells or a hybrid series and parallel connected string of solar cells), for example, a solar cell or combination of electrically connected solar cells having an open circuit voltage, for instance, mostly in the range of 4.5-10V. Depending on the solar cell technology and the number of solar cells in a string of electrically connected solar cells (and the environmental shading and soiling conditions), the open-circuit voltage range of the solar cell or string of electrically connected solar cells may be a different voltage range, and the upper end of the voltage range may be as high as 24 V or even larger (and the lower end of the voltage range being as low as about 3 V). Current flow between solar cell(s) output and MPPT inputs may be in the range of 0 to 15 amperes and more often in the range of 0 to 4 amperes.

The positive and negative input leads of each MPPT power optimizer (e.g., leads shown as positive MPPT input lead V_(P) 10 and negative MPPT input lead V_(M) 12 of MPPT package 6) are electrically connected to the positive and negative leads of a corresponding solar cell or combination of electrically connected solar cells (e.g., leads shown as positive solar cell output lead 22 and negative solar cell output lead 24). The positive and negative output leads of each MPPT optimizer (e.g., positive MPPT output lead V_(SW) 14 and negative MPPT output lead V_(M) 16 of MPPT package 6) are electrically connected to the distributed MPPT power optimizers in the system (e.g., MPPT packages 8 to n and associated components). Thus, each solar cell, or combination of electrically connected solar cells, and its corresponding MPPT power optimizer form a circuit for substantially independent or autonomous power optimization and also electrical connections with additional solar cells and corresponding MPPT power optimizers (e.g., solar cell(s) and MPPT optimizer circuits as shown in FIG. 1), in a system comprising a plurality of MPPT power optimizers and a plurality of associated solar cells or strings of electrically connected solar cells. The resulting electrically connected solar cells and corresponding MPPT optimizers have a positive output lead and a negative output lead (e.g., positive system output lead 18 and negative system output lead 20) for electrical connections, for example to additional systems, modules, load, or the electrical grid through an inverter.

Capacitor C_(IN) provides power stabilization and improves noise immunity, for example C_(IN) capacitance value may be about 5 μF or higher for a 2.24 A load current and may advantageously be positioned as close to the MPPT package power supply and input positive connection pin V_(P) as possible. V_(M) is a power connection pin connecting to the solar cell (or string of electrically connected solar cells) negative voltage and V_(P) is a power pin connecting to the solar cell negative voltage. V_(SW) is a power switching output, SW is power switching connection output, Boost is a power boost connection, and C_(BST) is a boost capacitor. C_(BST) may connected across a positive output lead and a boost lead of the MPPT package and the boost lead may be connected to the gate drive boost input of the high side field effect transistor (M1). The value of the boost capacitor may also be about 5 μF. A Schottky barrier rectifier or SBR (e.g., Schottky barrier rectifier 26 in FIG. 1) provides a current path to bypass a solar cell (or a string of electrically connected solar cells), and corresponding MPPT power optimizer circuit. Schottky barrier rectifier 26 having its cathode attached to positive lead 14 and anode attached to negative lead 16. C_(OUT) acts a filter for power inverter and may also be positioned in the Invertor package. Additional parasitic inductive filtering exists due to the wiring connected among various components. Additionally and if necessary, at least one inductor component may be placed in series within connections 18 and/or 20 to serve as filter in conjunction with the capacitor C_(OUT). The MPPT package may also have additional electrical leads for MPPT package testing and evaluation.

Thus, the MPPT power optimizer having an MPPT IC package and associated components optimizes the power harvesting of a corresponding solar cell or combination of electrically connected solar cells (e.g., solar cell or string of electrically connected 2 in FIG. 1) substantially autonomously and fairly independent of other electrically connected solar cells—in other words, the MPPT power optimizer having an MPPT IC package and associated components may optimize the power harvesting of a corresponding solar cell (or a string of electrically connected solar cells) independent of the other cells (and the other MPPT power optimizers) in the same string of series-connected (or hybrid series and parallel connected) MPPT power optimizers.

The MPPT power optimizer may work together with an online DC-to-AC power inverter (or a DC-to-DC power converter). A panel of solar cells is often made of a plurality (e.g., 60, 72, 96, 108, or another number) of solar cells, usually connected in electrical series. A DC-to-AC power inverter (known as inverter) connects to either one or a plurality of solar modules (with each module having a plurality of solar cells within the module laminate) and converts the solar photovoltaic (PV) system DC voltage and current to an AC line voltage and current, and sources the power to the load (such as electrical grid). The inverter may also provide a global (as opposed to distributed local) critical maximum-power-point tracking (MPPT) function for the entire solar system attached to and supported by the inverter. Using its MPPT function, the inverter loads the solar PV system such that the peak power (i.e., global maximum-power point) is reached and maintained at the system level. In other words, the inverter scans or walks up the system power vs voltage curve (see FIG. 5 showing a power vs voltage graph) in a power vs voltage function over a range of system voltages till the global maximum power is discovered and maintained.

For an individual solar cell, or a sub-panel combination of solar cells in a string of electrically connected solar cells (e.g., a combination of three to six solar cells in series string of a plurality of solar cells within a module laminate), a maximum-power-point tracking (MPPT) power optimizer must “pass” the solar cells energy to the panel string for the inverter to see this max power point. If all solar cells in the panel are operating normally (and approximately equal, such as when there is no localized shading or soiling), the MPPT power optimizer will stay in the so-called “pass-through” mode of operation. The solar panel operates best when all solar cells deliver the same photogeneration current in a string of series-connected solar cells. If for some reason (such as an external shading or soiling event) a solar cell (or a string of electrically connected solar cells) cannot support the required current, then that cell's output voltage will drop. If permitted to drop too low the cell (or cell string) and solar module will not operate at peak power. With the MPPT power optimizer forming a circuit with the cell (on the cell level), or forming a circuit with a sub-panel combination of solar cells electrically connected in a string, it measures the cells or sub-panel string combination of solar cells open circuit voltage, calculates a ratio or fixed multiplier of that voltage based on a predetermined constant (e.g., 0.76 times that voltage) and uses this point as the approximate MPPT point of the cell or sub-panel string combination of solar cells. The predetermined constant is selected to provide consistent power optimization and may a factor less than one and more often in the range of 0.70 to 0.85 and particularly often in the range of 0.75 to 0.85. Alternatively, the approximate MPPT point may be based on a fixed constant ratio or multiplier of the actual maximum power voltage (VNM) of the solar cell(s). If the cell (or string of electrically connected solar cells) loaded voltage reaches this point, the MPPT power optimizer will start to regulate the input voltage of the cell to the MPPT point thus maximizing power harvesting (the optimizer operates in the “optimizer region” shown in FIG. 5).

Solar cells within the same module laminate (for instance, in a 60-cell or 72-cell or 96-cell solar module) may produce varying amounts of power (for instance, due to partial shading and soiling events as well as manufacturing variation). Thus, a purpose of the MPPT power optimizer is to handle cases where a solar cell (or multiple solar cells electrically connected in a string) cannot support the current sourced through electrically connected solar cell system (e.g., a module or panel), such as in the case of a solar cell (or string of electrically connected solar cells) being shaded. Without the MPPT power optimizer, when a solar cell (or string of electrically connected solar cells) is shaded, the whole system (e.g., the whole solar module or panel) must reduce its current to accommodate the shaded cell or the shaded string of connected solar cells within the module laminate, resulting in loss of power in the whole system (e.g., module or panel and subsequently the PV system comprising a plurality of PV modules). The distributed MPPT power optimizer keeps the whole system (e.g., module or panel) running at or near its peak power point by utilizing multiple modes of operation for maximum power harvest and operational efficiency (minimum dissipation losses).

Additionally, the power production of a particular solar cell (or a string of electrically connected solar cells) may vary significantly. This variance may be due to the amount of light received, for example shading in addition to irradiance variations from sunrise till sunset, temperature, solar cell structural failures, or a number of other solar cell external and internal factors. A stronger solar cell produces higher power and a weaker solar cell generates lower power. The multiple modes of operation of the MPPT power optimizer provide increased power harvesting and efficiency from the optimized solar cell or combination of solar cells (or string of electrically connected solar cells). Besides the switching optimization mode of operation, the MPPT power optimizer provided herein may have an active bypass mode of operation, and a pass-through mode of operation. The MPPT power optimizer may further have a sleep (shut-down) mode and a passive bypass mode utilizing a rectifier such as a Schottky barrier rectifier (SBR).

FIG. 2 is a functional block diagram of an exemplary multi-modal MPPT power optimizer. Solar cell (or a string of electrically connected solar cells) is electrically connected to integrated circuit MPPT IC 30 through positive and negative leads on the solar cell (or string of electrically connected solar cells) and MPPT IC. MPPT IC negative input lead and positive input lead may be connected together to form a common lead in the MPPT IC. Similar to capacitor C_(IN) shown in FIG. 1, C1 is a capacitor for power stabilization and noise immunity improvement. And similar to Schottky barrier rectifier 26 shown in FIG. 1, D1 Schottky barrier rectifier (also called a Schottky diode or SBR) provides a current path to bypass the solar cell (or string of electrically connected solar cells) and corresponding MPPT IC 30.

SAMPLE and HOLD (S&H) is a circuit that measures the open-circuit voltage V_(OC) of the solar cell (or string of electrically connected solar cells). This circuit measures the voltage and calculates a ratio or multiplier of this value (e.g., a factor 0.76 multiplied by the measured open-circuit voltage, as described herein) as the corresponding maximum power point set-point for the solar cell (or string of electrically connected solar cells). The multiplier constant may be a value in the range of 0.60 and 0.90, preferably a constant in the range of 0.70 to 0.85 (e.g., 0.76 as mentioned previously). The maximum power point set-point is then digitized (using the ADC) and stored for the other functional blocks to use. Advantageously, SAMPLE and HOLD (S&H) may be a timing circuit having an analog-to-digital converter (ADC) based architecture to minimize MPPT IC power consumption and support longer sample and hold times (e.g., sample and hold times on the order of seconds to minutes). In the case of an ADC based architecture, an analog-to-digital converter (ADC) stores the number and a digital-to analog-converter (DAC) sends the stored value to the error amplifier and compensation. Generally, the sample and hold circuit may use periodic open circuit voltage sampling pulses for periodic measurements of open circuit voltage at a specified sampling period, sampling frequency, and sampling pulse duration for each sampling pulse. The sampling period may be in the range of seconds (e.g., in the range of 1 to 100 seconds and more preferably from in the range of 2 to 20 seconds). The sampling frequency may be in the range of 0.01 hertz to more than one hertz and more preferably in the range of 0.05 hertz to 0.5 hertz. The sampling pulse duration may be in the range of less than 100 micro-seconds up to 10 milli-seconds, more particularly in the range of 100 micro-seconds up to 1 milli-seconds, and advantageously in the range of 300 micro-seconds up to 800 micro-seconds.

Error amplifier and compensation compares the voltage of the solar cell (or string of electrically connected solar cells) to the maximum power point setpoint from the SAMPLE and HOLD circuit. If the solar cell (or string of electrically connected solar cells) voltage is above the SAMPLE and HOLD maximum power point set-point, then M1 is turned on and M2 is turned off. If the solar cell (or string of electrically connected solar cells) voltage is below the maximum power point set point then M1 is turned off and M2 is turned on. In this mode, M1 and M2 will continue to switch back and forth in a controlled frequency (e.g., a 500 kHz frequency) and a controlled duty cycle (greater than 0% and less than 100%), thus maintaining the solar cell(s) voltage at or close to its maximum power point.

The FET DRIVERS circuit provides the necessary power to switch M1 and M2 FET (Field Effect Transistor) gates on and off. M1 may be an n-channel field-effect transistor (NMOS). M1 may require a voltage above the solar cell (or string of electrically connected solar cells) voltage rail. An internal charge pump and low impedance switch may be used for this case. M2 may be an n-channel field-effect transistor (NMOS). M2 may require a simpler low impedance driver from minus to solar cell (or string of electrically connected solar cells) voltage to work. FET Drivers also have internal current sensing which turns off the gate drive in the event of an over-current condition.

ENABLE and UVLO is an enabling and under voltage lockout circuit. Enable is a signal which can turn on and off the MPPT IC functionality. Under Voltage Lock Out (UVLO) monitors the solar cell (or string of electrically connected solar cells) voltage, and if the voltage is too low for the MPPT IC to safely operate, the MPPT IC is disabled until the solar cell (or string of electrically connected solar cells) voltage is high enough to safely operate the MPPT IC (e.g., when solar cell or string of electrically connected solar cells power generation is restored to normal operating conditions). Enable 32 is an input pin so it is shown external to the IC.

M1 NMOS and M2 NMOS are power field effect transistors (FET), for example MOSFET switches, used to switch the power from the solar cell (or string of electrically connected solar cells) to the corresponding solar module. M1 NMOS is a high-side Pass field-effect transistor (FET) that delivers power and M2 NMOS is a low-side Synchronous (Sync) field-effect transistor (FET) with lower power loss than a diode (e.g., Schottky barrier rectifiers 26 in FIG. 1 and D1 in FIG. 2). FET DRIVERS are field effect transistor gate drivers for M1 NMOS and M2 NMOS. While MOSFET is advantageous for low power consumption, MESFET, high-electron mobility transistors, and bipolar junction transistors may also be used as switches.

To maximize power harvest and minimize power losses (e.g., minimize MPPT IC insertion loss), the multi-modal maximum-power-point tracking (MPPT) power optimizer operates in multiple operating modes. The multi-modal maximum-power-point tracking (MPPT) optimizer has functional operating modes (also called states) of active bypass mode, switching MPPT optimization mode, and pass-through mode dependent on the power (measured by voltage) generated by a connected solar cell (or string of electrically connected solar cells) as well as a desired maximum power point set-point based on ratio (or fixed constant multiplier) of the open circuit voltage of the connected solar cell (or string of electrically connected solar cells). The operating modes may provide a pass-through or bypass circuit or may adjust the input voltage conditions of the multi-modal maximum-power-point tracking (MPPT) power optimizer (e.g., by loading the circuit) based on the output voltage of the solar cell (or string of electrically connected solar cells) in order to generate maximum power based on the IV curve (i.e., current vs. voltage curve) for that solar cell or combination of electrically connected solar cells. In other words, the adjustable switching duty cycle of a switching DC-to-DC power converter (e.g., operating at a specified switching oscillator frequency) may be adjusted (between 0% and 100% duty cycle) such that solar cell or combination of electrically connected solar cells receives a load impedance that corresponds to its maximum power point bias point (or a bias point sufficiently near its maximum power point). The specified switching oscillator frequency may be in the range of 100 kilo-hertz to 5 mega-hertz, more particularly in the range of 100 kilo-hertz to 5 mega-hertz, and advantageously in the range of 300 kilo-hertz to 700 kilo-hertz. A shut-down mode (also called sleep-mode) and passive bypass mode further enhance automated functionality, power harvesting, and efficiency. In the shut-down mode, the MPPT IC is does not perform any function and sleeps (powered down, for instance, at night when the solar cells do not generate any power). The passive bypass mode (using SBR) provides a complete bypassing of the MPPT and its associated solar cell (or string of electrically connected solar cells) when there is a failure of the MPPT chip and or its associated solar cell (or string of electrically connected solar cells), hence, preserving system-level functionality for the overall solar PV system.

Threshold/transition voltage guidelines described for the MPPT optimization operating modes may be different for different solar cells or combinations of solar cells as well as different MPPT optimization components (e.g., depending on solar cell technology, number of solar cells in a string of electrically connected solar cells, and solar system characteristics). Parasitic inductance of the wiring connecting the solar cell(s) is used to filter and average current and voltage (i.e., filter the current and voltage) and also control peak current, hence, eliminating the need for dedicated inductor components for each MPPT IC. This innovation, in combination with high frequency use, allows for reduced insertion loss (and reduced cost and enhanced reliability) and substantially reduced optimizer size as an inductor component for filtering and current averaging is avoided by instead relying on the wiring elements required for electrical connections among solar cells and MPPT ICs. Delayed optimizing mode transition may increase the stability of system-level MPPT by filtering out sub-optima power point maxima.

FIG. 3 shows a representative timing diagram for a sample and hold (S&H) circuit to illustrate MPPT optimizer timing. During operation, the timing circuit samples the solar cell (or string of electrically connected solar cells) open circuit voltage (V_(OC)). Solar cell V_(OC) sampling is critical for operation when the high-side FET (M1) is turned off and is part of V_(OC) discovery. The V_(OC) sampling may be queried about every second (the sampling period may be longer, for instance, one measurement up to every 30 seconds, or shorter, for instance, one measurement down to every 100 milliseconds) as the solar cell open circuit voltage (V_(OC)) may vary quickly (e.g., due to intermittent shading events or ambient temperature changes).

V_(OC) sampling occurs by turning off the Pass nFET (high-side nFET M1) and turning on the Sync nFET (low-side nFET M2). This accomplishes two results: first it unloads the solar cell (or string of electrically connected solar cells) and puts it in open-circuit condition, and second it shorts the output so the solar panel current may keep flowing without disruption. While the Pass nFET (high-side nFET M1) is off, the circuit must wait for the C_(IN) capacitor to charge up to V_(OC). For example, using a 4.7 μF capacitor, plus considerable solar cell distributed capacitance, and for a 2.27 amp solar cell, the C_(IN) may take approximately 250 μSec to charge up to V_(OC). Advantageously, the circuit may permit 320 μS of charge wait time to enable any solar cell power generation condition (e.g., a very weak cell having a 0.2 A capability would still meet the timing requirement). After the V_(OC) is measured the Sync FET is turned off and the Pass FET is turned on and normal operation is restored.

When the solar cell (or string of electrically connected solar cells) voltage (solar cell positive and negative voltage differential V_(P)−V_(M)) is greater than a desired threshold, for example V_(P)−V_(M) in the range 5V to 10.5V Rising (e.g., in an increasing power generation solar cell condition such as sunrise) and 4.75V to 10.5V Falling (e.g., in a decreasing power generation solar cell condition such as sunset)), and V_(P)−V_(M) is greater than a desired ratio (or fixed constant multiplier of less than 1) of its open circuit voltage V_(OC), for example 0.76 of the V_(OC), then the MPPT power optimizer operates in pass-through mode. When the solar cell (or string of electrically connected solar cells) voltage (V_(P)−V_(M)) is greater than a desired threshold, for example V_(P)−V_(M) in the range 5V to 10.5V Rising (increasing such as in the case of sunrise) and 4.75V to 10.5V Falling (decreasing such as in the case of sunset), and V_(P)−V_(M) is less than a desired ratio (or fixed constant multiplier of less than 1) of its open circuit voltage V_(OC), for example 0.76 of the V_(OC), then the MPPT optimizer operates in the switching optimizing mode.

With reference to FIGS. 1 and 2, the input capacitor (C_(IN) in FIG. 1 and C1 in FIG. 2) advantageously may have a value greater than or equal ˜4.7 μF. The boost capacitor (C_(BST) in FIG. 1) advantageously may have a value greater than or equal to ˜4.7 μF. For the Under Voltage Lockout UVLO (ENABLE and UVLO in FIG. 2), the reference and the circuit remain reset until the (V_(P)−V_(M)) crosses UVLO threshold.

Ideally the MPPT IC will primarily operate in pass-through mode during the daytime (pass-through mode operating when solar cells, or a combination of solar cells, are strong and there is no shading) and will primarily operate in shutdown mode during the nighttime (when there is no power generation by the solar cells). Operating modes optimizing mode (also called switching mode or switching optimization mode or switching optimizing mode), active bypass mode, and passive bypass mode provide increased power harvesting and improved operational reliability during a wide range of power generation conditions and can also serve as transition modes between pass-through mode and shut-down mode. Other key benefits of these transitional modes include improved system level and MPPT IC power efficiency, reliability, and overall fault tolerance.

Pass-through mode is the operating mode when the solar cell, or combination of solar cells in an electrically connected string, is generating voltage both over a certain threshold (and up to a maximum allowed solar cell voltage) and over a set a ratio of the open circuit voltage (V_(OC)) of the solar cell. Thus, in a solar PV system as provided, pass-through mode operates when the current of the solar cell, or combination of solar cells in a string, is in the same range as the system (e.g., module or panel) current. Current matching throughout the system may be indicative of an absence of localized shading.

With reference to FIG. 2, in pass-through mode the High side FET M1 is turned ON and the Low side FET M2 is turned OFF. Thus, pass-through mode permits the module current to fully pass through M1 and the solar cell. In pass-through mode the High Side nLDMOS (e.g., M1 in FIG. 2) is on 100% of the time between V_(OC) sampling pulses (e.g., with sampling frequency of one sample every two to twenty seconds, or over a wider range of one sample every 0.1 to 60 seconds). A Pass-Through efficiency of 99.5% may be achieved by a High Side nLDMOS with Rds-on=16 mOhm at Standard Test Condition temperature 25° C. This relatively low on-state source-drain resistance for the high-side FET M1 ensures sufficiently low ohmic losses during the pass-through and switching modes of operation.

Exemplary pass-through mode operating thresholds include when the solar cell voltage (V_(P)−V_(M)) is in the range 5.0V to 10.5V Rising (e.g., in an increasing power generation solar cell condition such as sunrise) and 4.75V to 10.5V Falling (e.g., in a decreasing power generation solar cell condition such as sunset) and is above 0.76 of the V_(OC) (i.e., open circuit voltage multiplied by 0.76).

The MPPT power optimizer has 100% duty cycle operation in pass-through mode (i.e., no switching optimization during the pass-through mode of operation). As the input voltage approaches the output voltage, the converter turns the high side N-channel transistor (high side nFET M1, also referred to as Pass FET) continuously. In this mode the output voltage (V_(OUT)) is equal to the input voltage minus the voltage drop across the N-channel transistor: V_(OUT)=(V_(P)−V_(M))−I_(LOAD) (R_(DSON)+R_(L)); where (V_(P)−V_(M)) is solar cell voltage, R_(DSON) is N-channel high side (high side nFET M1, also referred to as Pass FET) switch ON resistance, I_(LOAD) is output current, and R_(L) is inductor (or wiring) DC resistance.

Optimizing (or Switching) mode is the operating mode when the solar cell, or combination of solar cells connected in a string supported by an MPPT IC, is generating voltage both over a certain threshold (and up to a maximum allowed solar cell voltage) and below a set a ratio (or fixed constant multiplier) of the open circuit voltage (V_(OC)) of the solar cell. This may occur when the solar cell, or combination of solar cells in an connected string, are weaker as compared to other cells in the panel (e.g., lower efficiency due to manufacturing variation) or there is mild to heavy shading or variable shading (optimizing mode operates in a larger range of shading conditions). The weak or shaded solar cell, or combination of solar cells in a connected string, cannot deliver the current of other panel cells which pulls down voltage on the weak or shaded solar cell, and once the voltage reaches a certain ratio of V_(OC) the MPPT IC transitions operating modes from pass-through mode to optimizing mode.

Advantageously, transitioning out of optimizing mode may be somewhat delayed (e.g., for about twenty to thirty milliseconds). This delay may benefit an overall solar PV system inverter global MPPT as it adjusts its power points and may allow an overall system to have a single power point (mono-maximal power point) without a need for sub-optima maxima power points. By filtering out sub-optima maxima, a more stable maximum power is provided which is more readily discoverable to string and central inverters with built-in MPPT functions.

During pass-through mode, the MPPT IC performs an open circuit sample (V_(OC)). V_(OC) sampling is performed by turning off the high side FET M1 and thus turning off the current from the solar cell creating an open circuit. The solar cell (or string of electrically connected solar cells) voltage will rise and a voltage sample is taken and stored. M1 turns back on and the solar cell (or string of electrically connected solar cells) is again loaded and its voltage drops. If the voltage drops below a predetermined level of V_(OC) (e.g., below 0.76 multiplied by the measured V_(OC)), then the switching optimization mode starts. M1 will be turned on and off (e.g., at a frequency of ˜500 kHz) in a controlled pulse width modulated condition that keeps the cell voltage at the predetermined V_(OC) (e.g., 0.76 multiplied by V_(OC)). This maintains the cell voltage at its peak operating point (maximum power point known as MPP). M2 does the opposite of M1 and turns on when M1 turns off. This permits the solar module current to pass unimpeded through the module while M1 is off. Thus, in optimizing mode the power delivered by the solar cell (or string of electrically connected solar cells) is the maximum available although reduced due to shading or perhaps due to a weak solar cell.

Exemplary optimizing mode operating thresholds include when the solar cell voltage (V_(P)−V_(M)) is in the range 5.0V to 10.5V Rising (e.g., in an increasing power generation solar cell condition such as sunrise) and 4.75V to 10.5V Falling (e.g., in a decreasing power generation solar cell condition such as sunset) and is less than 0.76 multiplied by V_(OC) (solar cell or string of connected solar cells open circuit voltage). The max voltage value 10.5V indicating a maximum voltage the solar cell(s) may generate or a maximum voltage the MPPT IC and components may support.

Active bypass mode is the operating mode when more than about one watt/m² of irradiance power is received by the solar cell or combination of solar cells but the solar cell or combination of solar cells may be heavily shaded with respect to the rest of the solar module. Active bypass mode provides for a smooth low-loss turn on/off transition to reduce electromagnetic/radio frequency interference and electromagnetic emission. Additionally, active bypass mode may act as a fail-safe due to higher temperatures (e.g., 110° C. such as in the case of a fire) to turn the system off more smoothly. The voltage threshold for active bypass mode may be set as the UVLO threshold for the MPPT IC on the low end and a minimal threshold to contribute power (or not be a power drain) to electrically connected solar cells on the high end, assuming these electrically connected solar cells are operating under minimal ideal conditions. In this solar cell power generation condition the solar cell, or combination of solar cells, does not have any power to deliver but there is enough voltage to activate the MPPT IC (i.e. a heavily shaded cell). In active bypass mode, the solar cell, or combination of solar cells, does not deliver any power to the panel and nor does it cause appreciable power loss by using a bypass circuit (e.g., super barrier rectifier)—in other words the cell does not deliver power but it does not lose power as there is much less heat dissipation and insertion loss. The high end value in the active bypass mode voltage range may be determined as a sufficiently low voltage such that in active bypass mode power harvesting is not compromised or lost. In heavily shaded conditions the photogenerated current and maximum power capabilities may drop by orders of magnitude. Such a solar cell power generation condition would occur when a solar cell or string of solar cells in a module is very heavily shaded such that it cannot generate appreciable power or current and cannot keep up with the unshaded solar cells and strings in the module—thus the shaded solar cells or string of solar cells is bypassed. Active bypass mode provides a lower loss bypass mode than a bypass circuit (e.g., a bypass circuit using an SBR). The high end value in the active bypass mode voltage range may be based on modeling of the V_(OC) of a solar cell or string of solar cells under heavily shaded conditions at a high operating temperature (e.g., 65° C.).

As an illustrative example, alternatively in a heavily shaded low power generation condition without an active bypass mode the bypass circuit (e.g., Schottky barrier rectifier) would be forward biased resulting in a loss of approximately 0.6V times the module current (e.g., 0.6×4 A=2.4 W lost). However, in active bypass mode M1 is turned OFF and M2 turned ON thus shorting the output and bypassing the current with only a small loss of power (e.g., if M2 is a 34 mOhm resistance FET, the loss would be approximately 4²×0.034=0.54 W resulting in savings of almost 2 W as compared to the 2.4 W loss in the illustrative example above). When the MPPT IC is in active bypass mode, the High Side nLDMOS is OFF and the Low Side nLDMOS is ON 100% of the time. Thus, active bypass mode may act as an intermediate stage which turns on at low power and reduces the loss associated with a bypass circuit (e.g., SBR) because it turns on the gate of the low side nLDMOS, resulting in increased efficiency. The active bypass mode operating thresholds may be used to set the minimum threshold value for pass-through mode and optimizing mode and the maximum threshold value for passive bypass mode. Exemplary active bypass mode operating thresholds include when the solar cell (or string of electrically connected solar cells) voltage (V_(P)−V_(M)) is in the range 4.5V to 5.0V rising (increasing such as during sunrise) and 4.75V to 4.25V falling (decreasing such as during sunset).

Passive bypass mode is the operating mode when about less than one watt/m² of power is generated by the solar cell or combination of solar cells, such as in the case of severe shading (e.g., 1000× shading or 1/1000 of maximum sunlight), and the MPPT IC cannot operate. Moreover, this passive bypass mode provides fault tolerance and allows for the module current to bypass the MPPT IC and its associated solar cell (or string of electrically connected solar cells), if and when there is a failure of the MPPT IC and/or its associated solar cell (or string of electrically connected solar cells), hence, providing continued system-level functionality even in case of a component failure. In this state the MPPT IC shuts down, turning off both M1 and M2, and the module/system current will then be forced to flow through the bypass circuit (shown as a Schottky barrier rectifier 26 in FIG. 1) thus forward biasing the bypass circuit. Although these instances may be considered rare, passive bypass mode is used to minimize losses across the entire system (e.g., module or panel) by preventing the entire system from not generating power. Additionally, the passive bypass mode provides a controlled turning off and on of the MPPT IC resulting in a more reliable MPPT IC. Again as discussed, the passive bypass mode also provides an additional fault tolerance mode in the case of any MPPT IC failure event (e.g., the integrated circuit itself or its electrical connections) as the bypass circuit (e.g., Schottky barrier rectifier) takes over and allows overall solar module to function except for the failed sub-block. The bypass circuit may utilize a diode component such as Schottky barrier rectifier (SBR) or a PN junction diode. In passive bypass mode, a bypass circuit is on (e.g., a diode such as super barrier rectifier Schottky barrier diode: SBR) is on and the High Side nLDMOS (M1) and Low Side nLDMOS (M2) are both off.

Exemplary passive bypass mode operating thresholds include when the solar cell voltage (V_(P)−V_(M)) is in the range 0.0V to 4.5V rising (increasing such as during sunrise) and 4.25V to 0V falling (decreasing such as during sunset) and V_(SW)−V_(M)<−0.8V.

Shutdown mode (also called sleep mode) is the operating mode when the solar cell or combination of solar cells in a string is not generating any appreciable voltage and power, for example at night or when completely shaded. In other words, shutdown mode operates when there is not enough power to power the MPPT IC (e.g., the UVLO threshold is not met such as when V_(P)−V_(M) is less than one volt) and the MPPT IC is off. Exemplary shutdown mode operating thresholds include when V_(P)−V_(M)=0V and V_(SW)−V_(M)>−0.7V.

FIG. 4 is a flow chart of multi-modal MPPT operation based on the exemplary operating mode threshold voltages provided.

FIG. 5 is a power vs. voltage graph showing optimizer mode and pass-through voltage operating conditions.

FIG. 6A is a more detailed functional block diagram of that shown in FIG. 2. For example, HSG of FIG. 6A is M1 of FIG. 2 and LSG of FIG. 6A is M2 of FIG. 2. For example, additional detailed electronic circuit functionality and components include vdd, ibias and bandgap. As identified in FIG. 6A, FIGS. 6B and 6C and 6D are expanded views of FIG. 6A.

Among other components, expanded view FIG. 6B shows the sample and hold and the enable circuit. The solar cell voltage is resistor divided down, a sample of this voltage is taken and digitally stored with an ADC. A DAC is used to restore the digital value to an analog voltage for a reference in and error amplifier stage. The Enable signal turns on and off all the Vdds and current biases.

Among other components, expanded view FIG. 6C shows the Error amplifier, ramp generator, clock, control logic, and all the voltage and current biases. The error amplifier compares the reference voltage for the DAC to the voltage of the solar cell. The error amplifier in combination with the control logic decides which mode the power FETs should be in. If the solar cell voltage is too high the High side FET will turn on, if the voltage is too low the low side FET will turn on. If the solar cell voltage is in the range when a PWM pulse is needed to regulate the solar cell at Max power point, then the PWM circuit will turn on and start regulating.

Among other components, expanded view FIG. 6D the two power FETs, the FET drivers, and current limiting. The purpose of the FET drivers is to supply the required current into the gates of the FETs so they can switch on and off at the required speed. The high side FET also may require a voltage higher than the cell voltage so a charge pump is implemented to accomplish this. In the event of an over current, and to protect the FETs from over current a sense circuit is used which will turn of the FETs. This is a cycle by cycle current limit.

With reference to the functional block diagram of FIG. 6A and the expanded views of FIG. 6A shown in FIGS. 6B, 6C, and 6D:

-   -   En: Enable Optimizer manages power-up and power down     -   8 bit ADC: 8 Bit Analog to Digital converter which is used to         digitize and store the open 0.076 of the PV panel Open Circuit         Voltage     -   8 bit DAC: 8 Bit Digital to Analog Converter is used to set the         target voltage VDAC_MPP for the error amplifier and achieve 0.76         of VOC     -   EA: Error amplifier is used to provide amplification and         feedback and stability for peak current mode controlled Solar         power DC to DC Converter     -   Soft Landing: Softlanding is used to implement a smooth         transition from Open Circuit sampling to optimizing (Switching)         Mode or pass through mode     -   CGM_ID: Implements the CGM_ID parameter in the peak Current mode         control equation and provides a stable operating region in         Optimizing (Switching) Mode     -   Slope_Compensation: Slope Compensation avoids wide pulse narrow         pulse current loop instability and suppress the impact of the         Interference and noise in the system     -   HSFCC_SFMT: High Side Current Comparator “Start-Up Minimum T-On”         implemented the cycle by cycle current comparator to turn off         High Side nFET when the peak command current is exceeded     -   Control Logic: The Control Logic ensures that the High Side Gate         Driver (HSD) and Low Side Driver (LSD) are off during power up,         power down, Over temperature over current conditions. It also         ensures that the HSD and LSD are never on at the same time     -   BSREF: Boost Regulator is used to pride power for the High side         nFET Transistor     -   Anti_Current: Anti Current is used to prevent power loss and         destruction due to reverse current flowing into the Solar PV         panel     -   Osc: The Oscillator is used to provide a clock for the system     -   DAPB: Dark Active Bypass is used to implement the active bypass         when the solar irradiance is very low and the VOC is less than         4.75V approximately, for example     -   Bandgap: The Bandgap Voltage reference is turned on when the         power supply is above approximately 3.75V, for example, and is         used to provide voltage references and Bias current references         that are accurate and stable over temperature and semiconductor         process corners     -   UVLO: The Under Voltage Lock-out is used to ensure the solar         optimizer does not destroy itself during power up and power down     -   OTP: Over Temperature protection is used to turn of the         Optimizer when the Temperature of the die is above −135° F.     -   Awake: The Awake signal is a critical signal that enables the         digital control signals after all the Voltage References, Bias         Currents and power regulators have settled and the system is         ready to operate correctly the Following are Other Aspects and         Embodiments:

-   A1. A solar photovoltaic system, comprising:     -   a. A plurality of photovoltaic modules, each of said         photovoltaic modules having:         -   i. a plurality of (N) solar cells and a plurality of (M)             multi-modal maximum-power-point-tracking (MPPT) DC power             optimizers embedded within a protective module laminate,             wherein:             -   1. N and M and N divided by M are positive integers                 greater than 1;             -   2. the positive and negative input electrical leads of                 each of said multi-modal MPPT DC power optimizers are                 electrically connected to the positive and negative                 electrical leads of a plurality of N divided by M                 electrically connected string of solar cells;             -   3. the positive and negative output electrical leads of                 said plurality of (M) multi-modal MPPT DC power                 optimizers are connected to one another within said                 module laminate according to an MPPT electrical                 interconnection design;             -   4. each of said plurality of photovoltaic modules have                 at least one pair of positive and negative electrical                 power leads; and,             -   5. said plurality of photovoltaic modules are connected                 to one another according to a module electrical                 interconnection design     -   b. At least one electrical load connected to said plurality of         photovoltaic modules connected to one another according to said         module electrical interconnection design

-   B2. The solar photovoltaic system of claim 1, wherein said solar     cells are crystalline silicon solar cells.

-   C3. The solar photovoltaic system of claim 1, wherein said solar     cells are thin-film solar cells.

-   D4. The solar photovoltaic system of claim 1, wherein said     photovoltaic modules are crystalline silicon photovoltaic modules.

-   E5. The solar photovoltaic system of claim 1, wherein said     photovoltaic modules are thin-film photovoltaic modules.

-   F6. The solar photovoltaic system of claim 1, wherein each of said     multi-modal maximum-power-point-tracking (MPPT) DC power optimizers     is electrically powered by photovoltaic power of each of said     plurality of N divided by M electrically connected string of solar     cells.

-   G7. The solar photovoltaic system of claim 1, wherein each of said     multi-modal maximum-power-point-tracking (MPPT) DC power optimizers     has a multi-modal operation algorithm comprising pass-through mode,     switching MPPT optimization mode, and active bypass mode.

-   H8. The solar photovoltaic system of claim 1, wherein said at least     one electrical load is a DC-to-AC power inverter having at least one     built-in inverter maximum-power-point tracking (MPPT).

-   I9. The solar photovoltaic system of claim 8, wherein said at least     one built-in inverter MPPT performs global system-level MPPT control     and said plurality of (M) multi-modal MPPT DC power optimizers

-   J10. The solar photovoltaic system of claim 1, wherein said at least     one electrical load is a DC-to-DC power converter having at least     one built-in converter maximum-power-point tracking (MPPT).

-   K11. The solar photovoltaic system of claim 1, wherein said     protective module laminate comprises glass and encapsulant sheets     attached to first sides of said plurality of (N) solar cells and     plurality of (M) multi-modal maximum-power-point-tracking (MPPT) DC     power optimizers, and polymeric and encapsulant sheets attached to     second sides, opposite to said first sides, of said plurality of (N)     solar cells and plurality of (M) multi-modal     maximum-power-point-tracking (MPPT) DC power optimizers.

-   L12. The solar photovoltaic system of claim 1, wherein said     protective module laminate comprises glass and encapsulant sheets     attached to first sides of said plurality of (N) solar cells and     plurality of (M) multi-modal maximum-power-point-tracking (MPPT) DC     power optimizers, and glass and encapsulant sheets attached to     second sides, opposite to said first sides, of said plurality of (N)     solar cells and plurality of (M) multi-modal     maximum-power-point-tracking (MPPT) DC power optimizers.

-   M13. The solar photovoltaic system of claim 1, wherein N is an     integer between 10 and 1000.

-   N14. The solar photovoltaic system of claim 1, wherein N is an     integer between 30 and 300.

-   O15. The solar photovoltaic system of claim 1, wherein N divided by     M is an integer between 5 and 50.

-   P16. The solar photovoltaic system of claim 1, wherein N divided by     M is an integer between 10 and 30.

-   Q17. The solar photovoltaic system of claim 1, wherein each of said     plurality of N divided by M electrically connected string of solar     cells has a series-connected string of solar cells.

-   R18. The solar photovoltaic system of claim 1, wherein each of said     plurality of N divided by M electrically connected string of solar     cells has a hybrid series and parallel connected string of solar     cells.

-   S19. The solar photovoltaic system of claim 1, wherein said MPPT     electrical interconnection design is a series interconnection of     said plurality of (M) multi-modal maximum-power-point-tracking     (MPPT) DC power optimizers.

-   T20. The solar photovoltaic system of claim 1, wherein said MPPT     electrical interconnection design is a hybrid series and parallel     interconnection of said plurality of (M) multi-modal     maximum-power-point-tracking (MPPT) DC power optimizers.

-   U21. The solar photovoltaic system of claim 1, wherein said module     electrical interconnection design is a series interconnection of     said plurality of photovoltaic modules.

-   V22. The solar photovoltaic system of claim 1, wherein said module     electrical interconnection design is a hybrid series and parallel     interconnection of said plurality of photovoltaic modules.

-   W23. The solar photovoltaic system of claim 1, wherein each of said     plurality of (M) multi-modal maximum-power-point-tracking (MPPT) DC     power optimizers is made of one integrated circuit attached to a     printed-circuit board, and at least one capacitor connected to said     integrated circuit on said printed-circuit board, wherein said     printed-circuit board provides said positive and negative input     electrical leads and said positive and negative output electrical     leads for electrical interconnections.

-   X24. The solar photovoltaic system of claim 22, wherein said     printed-circuit board further has a Schottky-barrier rectifier     attached across said positive and negative output electrical leads     of said multi-modal MPPT DC power optimizer.

-   Y25. A solar photovoltaic module, comprising:     -   a. A protective module laminate;     -   b. a plurality of (N) solar cells and a plurality of (M)         multi-modal maximum-power-point-tracking (MPPT) DC power         optimizers embedded within said protective module laminate,         wherein:         -   i. N and M and N divided by M are positive integers greater             than 1;         -   ii. the positive and negative input electrical leads of each             of said multi-modal MPPT DC power optimizers are             electrically connected to the positive and negative             electrical leads of a plurality of N divided by M             electrically connected string of solar cells;         -   iii. the positive and negative output electrical leads of             said plurality of (M) multi-modal MPPT DC power optimizers             are connected to one another within said module laminate             according to an MPPT electrical interconnection design,             providing at least one pair of output electrical leads from             said plurality of (M) multi-modal MPPT DC power optimizers             connected to one another;     -   c. at least one pair of positive and negative electrical power         leads emanated from said protective module laminate and         electrically connected to said at least one pair of output         electrical leads of from said plurality of (M) multi-modal MPPT         DC power optimizers connected to one another.

-   Z26. The solar photovoltaic module of claim 25, wherein said solar     cells are crystalline silicon solar cells.

-   AA27. The solar photovoltaic module of claim 25, wherein said solar     cells are thin-film solar cells.

-   BB28. The solar photovoltaic module of claim 25, wherein said     photovoltaic module is a crystalline silicon photovoltaic module.

-   CC29. The solar photovoltaic module of claim 25, wherein said     photovoltaic module is a thin-film photovoltaic module.

-   DD30. The solar photovoltaic module of claim 25, wherein each of     said multi-modal maximum-power-point-tracking (MPPT) DC power     optimizers is electrically powered by photovoltaic power of each of     said plurality of N divided by M electrically connected string of     solar cells.

-   EE31. The solar photovoltaic module of claim 25, wherein each of     said multi-modal maximum-power-point-tracking (MPPT) DC power     optimizers has a multi-modal operation algorithm comprising     pass-through mode, switching MPPT optimization mode, and active     bypass mode.

-   FF32. The solar photovoltaic module of claim 25, wherein said     protective module laminate comprises glass and encapsulant sheets     attached to first sides of said plurality of (N) solar cells and     plurality of (M) multi-modal maximum-power-point-tracking (MPPT) DC     power optimizers, and polymeric and encapsulant sheets attached to     second sides, opposite to said first sides, of said plurality of (N)     solar cells and plurality of (M) multi-modal     maximum-power-point-tracking (MPPT) DC power optimizers, providing a     mono-facial solar photovoltaic module receiving light through one     side of said protective module laminate having said glass sheet.

-   GG33. The solar photovoltaic module of claim 25, wherein said     protective module laminate comprises glass and encapsulant sheets     attached to first sides of said plurality of (N) solar cells and     plurality of (M) multi-modal maximum-power-point-tracking (MPPT) DC     power optimizers, and glass and encapsulant sheets attached to     second sides, opposite to said first sides, of said plurality of (N)     solar cells and plurality of (M) multi-modal     maximum-power-point-tracking (MPPT) DC power optimizers, providing a     bi-facial solar photovoltaic module receiving light through both     glass-covered sides of said protective module laminate.

-   HH34. The solar photovoltaic module of claim 25, wherein N is an     integer between 10 and 1000.

-   II35. The solar photovoltaic module of claim 25, wherein N is an     integer between 30 and 300.

-   JJ36. The solar photovoltaic module of claim 25, wherein N divided     by M is an integer between 5 and 50.

-   KK37. The solar photovoltaic module of claim 25, wherein N divided     by M is an integer between 10 and 30.

-   LL38. The solar photovoltaic module of claim 25, wherein each of     said plurality of N divided by M electrically connected string of     solar cells has a series-connected string of solar cells.

-   MM39. The solar photovoltaic module of claim 25, wherein each of     said plurality of N divided by M electrically connected string of     solar cells has a hybrid series and parallel connected string of     solar cells.

-   NN40. The solar photovoltaic module of claim 25, wherein said MPPT     electrical interconnection design is a series interconnection of     said plurality of (M) multi-modal maximum-power-point-tracking     (MPPT) DC power optimizers.

-   OO41. The solar photovoltaic module of claim 25, wherein said MPPT     electrical interconnection design is a hybrid series and parallel     interconnection of said plurality of (M) multi-modal     maximum-power-point-tracking (MPPT) DC power optimizers.

-   PP42. The solar photovoltaic module of claim 25, wherein said module     electrical interconnection design is a series interconnection of     said plurality of photovoltaic modules.

-   QQ43. The solar photovoltaic module of claim 25, wherein said module     electrical interconnection design is a hybrid series and parallel     interconnection of said plurality of photovoltaic modules.

-   RR44. The solar photovoltaic module of claim 25, wherein each of     said plurality of (M) multi-modal maximum-power-point-tracking     (MPPT) DC power optimizers is made of one integrated circuit     attached to a printed-circuit board, and at least one capacitor     connected to said integrated circuit on said printed-circuit board,     wherein said printed-circuit board provides said positive and     negative input electrical leads and said positive and negative     output electrical leads for electrical interconnections.

-   SS45. The solar photovoltaic system of claim 44, wherein said     printed-circuit board further has a Schottky-barrier rectifier     attached across said positive and negative output electrical leads     of said multi-modal MPPT DC power optimizer.

-   TT50. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 49, wherein     said rectifier bypass mode utilizes a Schottky Barrier Rectifier     (SBR).

-   UU53. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 52, wherein     said specified open-circuit voltage sampling period is in the range     of about 2 seconds second up to about 20 seconds, corresponding to     said open-circuit sampling frequency being in the range of about     0.05 hertz up to about 0.5 hertz.

-   VV55. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 54, wherein     said specified voltage sampling duration is in the range of less     than 100 micro-seconds up to 1 milli-second.

-   WW56. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 55, wherein     said specified voltage sampling duration is in the range of 300     micro-seconds up to 800 micro-seconds.

-   XX58. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 57, wherein     said specified switching oscillator frequency is in the range of     about 200 kilo-hertz up to about 2 mega-hertz.

-   YY59. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 58, wherein     said specified switching oscillator frequency is in the range of     about 300 kilo-hertz up to about 700 kilo-hertz.

-   ZZ60. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said pass-through power efficiency is at least 95%.

-   AAA61. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 60, wherein     said pass-through power efficiency is at least 98%.

-   BBB62. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said optimizing power efficiency is at least 70%.

-   CCC63. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 62, wherein     said optimizing power efficiency is at least 85%.

-   DDD65. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said high-side field-effect transistor has an on-state     drain-to-source resistance of less than about 50 milli-ohms for said     pass-through mode of operation.

-   EEE66. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 65, wherein     said high-side field-effect transistor has an on-state     drain-to-source resistance of less than about 25 milli-ohms for said     pass-through mode of operation.

-   FFF67. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 48, wherein     said low-side field-effect transistor has an on-state     drain-to-source resistance of less than about 100 milli-ohms for     said active bypass mode of operation.

-   GGG68. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 67, wherein     said low-side field-effect transistor has an on-state     drain-to-source resistance of less than about 60 milli-ohms for said     active bypass mode of operation.

-   HHH69. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said pass-through mode of operation occurs when said high-side     field-effect transistor is on 100% of the time between said     open-circuit voltage sampling pulses.

-   III70. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 69, wherein     said adjustable switching duty cycle is 100% during said     pass-through mode of operation.

-   JJJ72. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said active bypass mode of operation occurs when said high-side     field-effect transistor is off and said low-side field-effect     transistor is on 100% of the time.

-   KKK73. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said active shut-down mode of operation occurs when the voltage     across said input positive and negative electrical leads for     electrical connections to positive and negative electrical leads of     said string of interconnected solar cells is too small to power up     said high-efficiency multi-modal maximum-power-point-tracking (MPPT)     DC power optimizer integrated circuit.

-   LLL74. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said voltage across said input positive and negative electrical     leads for electrical connections to positive and negative electrical     leads of said string of interconnected solar cells is less than     about 1 volt.

-   MMM75. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 49, wherein     said rectifier bypass mode of operation comprises a rectifier having     its anode and cathode electrically connected across said output     positive and negative electrical leads, with said rectifier cathode     electrically connected to said output positive lead and said     rectifier anode electrically connected to said output negative lead,     with said rectifier being forward biased and conducting current,     said high-side field-effect transistor switch being off, and said     low-side field-effect transistor switch being off.

-   NNN76. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 47, wherein     said input positive and negative electrical leads have an input     voltage because of electrical connections to said positive and     negative electrical leads of said string of interconnected solar     cells.

-   OOO77. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 76, wherein     said optimizing mode of operation regulates said input voltage to a     pre-determined optimum voltage.

-   PPP78. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 77, wherein     said pre-determined optimum voltage is equal to the product of said     open-circuit voltage (Voc) of said string of interconnected solar     cells and a pre-determined constant multiplying factor which is less     than 1.

-   QQQ79. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 78, wherein     said pre-determined constant multiplying factor is a number between     0.65 and 0.90.

-   RRR80. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 79, wherein     said pre-determined constant multiplying factor is a number between     0.70 and 0.85.

-   SSS81. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 78, wherein     said pre-determined constant multiplying factor is a number between     0.75 and 0.80.

-   TTT82. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 78, wherein     said pre-determined constant multiplying factor is 0.76.

-   UUU83. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 46, wherein     said integrated circuit is electrically powered by said string of     interconnected solar cells electrically connected and providing     supply voltage to said input positive and negative electrical leads.

-   VVV84. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 83, wherein     said supply voltage is less than 18 volts.

-   WWW85. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 84, wherein     said supply voltage is in the range of 3 volts and 15 volts.

-   XXX86. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 85, wherein     said supply voltage is in the range of 4 volts and 12 volts.

-   YYY87. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 86, wherein     said supply voltage is in the range of 4.5 volts and 10.5 volts.

-   ZZZ88. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 46, wherein     said analog-to-digital-converter (ADC) based architecture for sample     and hold enables reduced power consumption and relatively long     sample and hold times on the order of seconds to minutes.

-   AAAA89. A plurality of said high-efficiency multi-modal     maximum-power-point-tracking (MPPT) DC power optimizer integrated     circuits of claim 46, wherein a plurality of said strings of     interconnected solar cells are electrically connected to a plurality     of said input positive and negative electrical leads, and a     plurality of said output positive and negative electrical leads are     together connected in electrical series.

-   BBBB90. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 46, wherein a     capacitor is electrically connected across said input positive and     negative electrical leads.

-   CCCC91. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 46, wherein a     Schottky barrier diode (SBR) is electrically connected across said     output positive and negative electrical leads.

-   DDDD92. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 46, wherein     said low-profile integrated circuit package has a thickness of less     than 1 mm.

-   EEEE93. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 92, wherein     said low-profile integrated circuit package has a thickness of about     0.6 mm.

-   FFFF94. The high-efficiency multi-modal maximum-power-point-tracking     (MPPT) DC power optimizer integrated circuit of claim 46, wherein     said low-profile integrated circuit package has a center exposed     metallic pad electrically connected to said input negative     electrical and said output negative electrical lead, said center     exposed pad also enabling heat sinking.

-   GGGG101. The multi-modal maximum-power-point-tracking power     optimizer of claim 100, wherein said pre-determined constant factor     is a number between 0.70 and 0.85.

-   HHHH102. The multi-modal maximum-power-point-tracking power     optimizer of claim 101, wherein said pre-determined constant factor     is a number between 0.75 and 0.80.

-   IIII103. The multi-modal maximum-power-point-tracking power     optimizer of claim 102, wherein said pre-determined constant factor     is approximately 0.76.

-   JJJJ106. The multi-modal maximum-power-point-tracking power     optimizer of claim 96, wherein said electrical load is a DC-to-AC     power inverter having an inverter maximum-power-point tracking     circuit

-   KKKK107. The multi-modal maximum-power-point-tracking power     optimizer of claim 96, wherein said electrical load is a DC-to-DC     power converter having a converter maximum-power-point tracking     circuit

-   LLLL108. The multi-modal maximum-power-point-tracking power     optimizer of claim 106, wherein said inverter maximum-power-point     tracking circuit controls power optimization of said string of     electrically interconnected plurality of solar cells when said power     optimizer operates in said pass-through mode of operation.

-   MMMM109. The multi-modal maximum-power-point-tracking power     optimizer of claim 107, wherein said converter maximum-power-point     tracking circuit controls power optimization of said string of     electrically interconnected plurality of solar cells when said power     optimizer operates in said pass-through mode of operation.

-   NNNN110. The multi-modal maximum-power-point-tracking power     optimizer of claim 99, wherein said output string voltage is     regulated to be approximately equal to said transition voltage value     by adjusting said controllable switching duty cycle, when said     multi-modal maximum-power-point-tracking power optimizer operates in     said optimizing mode of operation.

-   OOOO111. The multi-modal maximum-power-point-tracking power     optimizer of claim 99, wherein said transition voltage value is     equal to the multiplication of the actual maximum-power voltage     (Vmp) of said string of electrically interconnected plurality of     solar cells by a pre-determined voltage multiplier factor less than     1.

-   PPPP112. The multi-modal maximum-power-point-tracking power     optimizer of claim 111, wherein said multiplier factor is between     0.85 and 1.

-   QQQQ113. The multi-modal maximum-power-point-tracking power     optimizer of claim 112, wherein said multiplier factor is between     0.88 and 0.95.

-   RRRR114. The multi-modal maximum-power-point-tracking power     optimizer of claim 112, wherein said multiplier factor is     approximately 0.90.

-   SSSS116. A plurality of said solar photovoltaic electrical power     generators of claim 95 interconnected to one another, wherein said     plurality of said power optimizer output positive and negative     electrical leads are connected in hybrid electrical series and     parallel.

-   TTTT117. The multi-modal maximum-power-point-tracking power     optimizer of claim 95, wherein said string of electrically     interconnected plurality of solar cells comprises a plurality of N     series-connected solar cells, with N being an integer between 5 and     30.

-   UUUU118. The multi-modal maximum-power-point-tracking power     optimizer of claim 117, wherein said string of electrically     interconnected plurality of solar cells comprises a plurality of N     series-connected solar cells, with N being an integer between 8 and     24.

-   VVVV119. The multi-modal maximum-power-point-tracking power     optimizer of claim 95, wherein said open-circuit voltage value (Voc)     is in the range of about 3 volts up to 24 volts.

-   WWWW120. The multi-modal maximum-power-point-tracking power     optimizer of claim 119, wherein said open-circuit voltage value     (Voc) is in the range of about 5 volts up to 15 volts.

-   XXXX121. The multi-modal maximum-power-point-tracking power     optimizer of claim 95, wherein said power optimizer input negative     electrical lead and said power optimizer output negative electrical     lead are electrically connected together to form a common lead in     said integrated circuit package.

-   YYYY122. The solar photovoltaic electrical power generator of claim     95, wherein said integrated circuit package is attached to a     printed-circuit board, and an input capacitor is connected across     said input positive and negative electrical leads on said     printed-circuit board, wherein said printed-circuit board provides     electrical leads connected to said input positive and negative     electrical leads and said output positive and negative electrical     leads for electrical interconnections.

-   ZZZZ123. The solar photovoltaic electrical power generator of claim     122, wherein a boost capacitor is connected across across said     output positive electrical lead and a boost lead of said integrated     circuit package on said printed-circuit board.

-   AAAAA124. The solar photovoltaic electrical power generator of claim     123, wherein said boost lead of said integrated circuit package is     electrically connected to the gate drive boost input of said     high-side field-effect transistor.

-   BBBBB125. The solar photovoltaic electrical power generator of claim     95, wherein said integrated circuit package further has an     electrical lead for enable and disable function and additional     electrical leads for electrical testing and evaluation of said     multi-modal maximum-power-point-tracking power optimizer.

-   CCCCC126. The solar photovoltaic electrical power generator of claim     95, wherein electrical current flowing between said string output     positive and negative electrical leads and said power optimizer     input positive and negative electrical leads is in the range of 0 up     to about 15 amperes.

-   DDDDD127. The solar photovoltaic electrical power generator of claim     126, wherein electrical current flowing between said string output     positive and negative electrical leads and said power optimizer     input positive and negative electrical leads is in the range of 0 up     to about 6 amperes.

-   EEEEE128. The solar photovoltaic electrical power generator of claim     127, wherein electrical current flowing between said string output     positive and negative electrical leads and said power optimizer     input positive and negative electrical leads is in the range of 0 up     to about 4 amperes.

-   FFFFF129. The solar photovoltaic electrical power generator of claim     96, wherein said multi-modal maximum-power-point-tracking power     optimizer operates in said pass-through mode of operation or said     optimizing mode of operation, when said output string voltage, known     as supply voltage, is in the range of approximately 5.0 volts to     10.5 volts when the voltage is rising, and approximately 4.75 volts     to 10.5 volts when the voltage is falling.

-   GGGGG130. The solar photovoltaic electrical power generator of claim     97, wherein said multi-modal maximum-power-point-tracking power     optimizer operates in said active bypass mode of operation when said     output string voltage, known as supply voltage, is in the range of     approximately 4.5 volts to 5.0 volts when the voltage is rising, and     approximately 4.25 volts to 4.75 volts when the voltage is falling.

-   HHHHH131. The solar photovoltaic electrical power generator of claim     96, wherein said multi-modal maximum-power-point-tracking power     optimizer operates in said optimizing mode of operation when at     least a portion of said string of electrically interconnected     plurality of solar cells is shaded.

-   IIIII132. The solar photovoltaic electrical power generator of claim     98, wherein said multi-modal maximum-power-point-tracking power     optimizer operates in said rectifier mode of operation, when said     output string voltage, known as supply voltage, is in the range of     approximately 0 volt to 4.5 volts when the voltage is rising, and     approximately 4.25 volts to 4.75 volts when the voltage is falling,     and voltage across said power optimizer output positive and negative     electrical leads is less than −0.8 volt.

-   JJJJJ133. The solar photovoltaic electrical power generator of claim     98, wherein said rectifier bypass mode of operation forward biases a     rectifier electrically connected with its cathode and anode     electrically connected to said power optimizer output positive and     negative electrical leads, respectively, and turns off both said     high-side field-effect transistor and low-side field-effect     transistor.

-   KKKKK134. The multi-modal maximum-power-point-tracking power     optimizer of claim 96, wherein said controllable switching duty     cycle is 100% during said pass-through mode of operation.

-   LLLLL135. The multi-modal maximum-power-point-tracking power     optimizer of claim 96, wherein said controllable switching duty     cycle is greater than 0% and less than 100% during said optimizing     mode of operation.

FIG. 7 is a table showing an MPPT optimizer consistent with FIG. 6A in different modes consistent with the exemplary operating mode thresholds described herein.

The foregoing description of the exemplary embodiments is provided to enable any person skilled in the art to make or use the claimed subject matter. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the innovative faculty. Thus, the claimed subject matter is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 

The invention claimed is:
 1. A high-efficiency multi-modal maximum-power-point-tracking (MPPT) DC power optimizer integrated circuit for optimization of photovoltaic power of a string of interconnected solar cells, comprising: a sample and hold circuit having periodic open-circuit voltage sampling pulses for periodic measurements of open-circuit voltage (V_(OC)) of said string of interconnected solar cells at a specified open-circuit voltage sampling period corresponding to a specified open-circuit voltage sampling frequency and for a specified open-circuit voltage sampling pulse duration for each of said periodic open-circuit voltage sampling pulses; an analog-to-digital-converter (ADC) based architecture for said sample and hold circuit for measuring the open-circuit voltage of said string of interconnected solar cells and calculating a multiplier of said open-circuit voltage as the maximum-power-point set-point, with said multiplier being a value in the range of 0.6 to 0.9; a high-side field-effect transistor switch (high-side FET switch); a low-side field-effect transistor switch (low-side FET switch); a DC-to-DC switching circuit operating at a specified switching oscillator frequency in the range of 100 kilo-hertz and 5 mega-hertz and with an adjustable switching duty cycle in the range of between 0% up to 100%; a multi-modal control algorithm providing shutdown mode of operation when said integrated circuit is turned off, a pass-through mode of operation having a pass-through power efficiency, an optimizing mode of operation having an optimizing power efficiency, and an active bypass mode of operation to increase photovoltaic power from string of interconnected solar cells, to mitigate the effects of electrical mismatches among a plurality of strings of interconnected solar cells, and to reduce electrical power losses; an under-voltage lockout (UVLO) circuit to monitor the voltage of said string of interconnected solar cells, to enable said active bypass mode of operation, and to protect said high-efficiency MPPT DC power optimizer integrated circuit during power up and power down; wherein said high-side FET switch is connected to a first FET driver capable of either turning it on to provide a low on-state drain-to-source resistance of less than 50 milli-ohms for the pass-through mode of operation, or turning it off to block current flow; wherein said low-side FET switch is connected to a second FET driver capable of either turning it on to provide a low on-state drain-to-source resistance of less than 100 milli-ohms for the active bypass mode of operation, or turning it off to block current flow; wherein said high-efficiency MPPT DC power optimizer integrated circuit operates in said active bypass mode of operation when the voltage of said string of interconnected solar cells falls below a UVLO threshold voltage setting while remains sufficiently large to avoid said shutdown mode of operation, by turning on said low-side FET switch and turning off said high-side FET switch; and a low-profile integrated circuit package having a plurality of electrical leads, including input positive and negative electrical leads for electrical connections to positive and negative electrical leads of said string of interconnected solar cells, and output positive and negative electrical leads, and having an exposed metallic pad electrically connected to the negative input and negative output leads for heat sinking.
 2. The high-efficiency multi-modal maximum-power-point-tracking (MPPT) DC power optimizer integrated circuit of claim 1, wherein said multi-modal control algorithm further includes a rectifier bypass mode of operation.
 3. The high-efficiency multi-modal maximum-power-point-tracking (MPPT) DC power optimizer integrated circuit of claim 1, wherein said optimization of photovoltaic power comprises an electronic circuit voltage regulator for regulating the operating voltage of said string of interconnected solar cells.
 4. The high-efficiency multi-modal maximum-power-point-tracking (MPPT) DC power optimizer integrated circuit of claim 1, wherein said specified open-circuit voltage sampling period is in the range of less than 1 second up to about 100 seconds, corresponding to said open-circuit voltage sampling frequency being in the range of about 0.01 hertz to more than 1 hertz.
 5. The high-efficiency multi-modal maximum-power-point-tracking (MPPT) DC power optimizer integrated circuit of claim 1, wherein said specified voltage sampling duration is in the range of less than 100 micro-seconds up to 10 milli-seconds.
 6. The high-efficiency multi-modal maximum-power-point-tracking (MPPT) DC power optimizer integrated circuit of claim 1, wherein said high-side field-effect transistor and said low-side field-effect transistor are n-channel field-effect transistors (NMOS transistors).
 7. The high-efficiency multi-modal maximum-power-point-tracking (MPPT) DC power optimizer integrated circuit of claim 1, wherein said optimizing mode of operation is a switching mode of operation with said high-side field-effect transistor being on with said adjustable switching duty cycle being greater than 0 and less than 100% of the time between said open-circuit voltage sampling pulses.
 8. A solar photovoltaic electrical power generator, comprising: a string of electrically interconnected plurality of solar cells, having at least a pair of string output positive and negative electrical leads having an output string voltage across them, with said output string voltage being in the range of 0 volt up to an open-circuit voltage (V_(OC)) value; a multi-modal maximum-power-point-tracking power optimizer, comprising: an analog-to-digital-converter (ADC) based architecture for supporting voltage sample and hold function for measuring said open-circuit voltage (V_(OC)) value of said string of electrically interconnected plurality of solar cells and calculating a multiplier of said open-circuit voltage (V_(OC)) value as the maximum-power-point set-point, with said multiplier being a value in the range of 0.6 to 0.9; a sample and hold circuit having periodic sampling pulses for periodic measurements of said open-circuit voltage (V_(OC)) value at a pre-determined sampling period corresponding to a pre-determined sampling frequency and for a pre-determined sampling pulse duration for each of said periodic sampling pulses; a high-side field-effect transistor switch (high-side FET switch); a low-side field-effect transistor switch (low-side FET switch); a DC-to-DC switching circuit operating at a pre-determined switching frequency in the range of 100 kilo-hertz and 5 mega-hertz and with a controllable switching duty cycle in the range of 0% up to 100%; a multi-modal power optimization control algorithm providing a shutdown mode of operation when said integrated circuit is turned off, a pass-through mode of operation having a pass-through power efficiency, an optimizing mode of operation having an optimizing power efficiency, and an active bypass mode of operation to deliver optimum photovoltaic electrical power from said string of electrically interconnected plurality of solar cells to an electrical load; an under-voltage lockout (UVLO) circuit to monitor the voltage of said string of electrically interconnected plurality of solar cells, to enable said active bypass mode of operation, and to protect said optimizer integrated circuit during power up and power down; wherein said high-side FET switch is connected to a first FET driver capable of either turning it on to provide a low on-state drain-to-source resistance of less than 50 milli-ohms for the pass-through mode of operation, or turning it off to block current flow; wherein said low-side FET switch is connected to a second FET driver capable of either turning it on to provide a low on-state drain-to-source resistance of less than 100 milli-ohms for the active bypass mode of operation, or turning it off to block current flow; wherein said power optimizer integrated circuit operates in said active bypass mode of operation when the voltage of said string of electrically interconnected plurality of solar cells falls below a UVLO threshold voltage setting while remains sufficiently large to avoid said shutdown mode of operation, by turning on said low-side FET switch and turning off said high-side FET switch; and an integrated circuit package having power optimizer input positive and negative electrical leads for electrical connections to said at least said pair of string output positive and negative electrical leads, and power optimizer output positive and negative electrical leads, and having an exposed metallic pad electrically connected to the negative input and negative output leads for heat sinking.
 9. The multi-modal maximum-power-point-tracking power optimizer of claim 8, wherein said multi-modal power optimization control algorithm includes a pass-through mode, an optimizing mode, and a shut-down mode of operation.
 10. The multi-modal maximum-power-point-tracking power optimizer of claim 9, wherein said multi-modal power optimization control algorithm further an active bypass mode of operation.
 11. The multi-modal maximum-power-point-tracking power optimizer of claim 9, wherein said multi-modal power optimization control algorithm further includes a rectifier bypass mode of operation.
 12. The multi-modal maximum-power-point-tracking power optimizer of claim 9, wherein said multi-modal power optimization control algorithm utilizes a transition voltage value obtained by multiplying said open-circuit voltage by a pre-determined constant factor.
 13. The multi-modal maximum-power-point-tracking power optimizer of claim 12, wherein said pre-determined constant factor is a number between 0.65 and 0.90.
 14. The multi-modal maximum-power-point-tracking power optimizer of claim 12, wherein said multi-modal maximum-power-point-tracking power optimizer operates in said pass-through mode of operation when said output string voltage is greater than said transition voltage value.
 15. The multi-modal maximum-power-point-tracking power optimizer of claim 12, wherein said multi-modal maximum-power-point-tracking power optimizer operates in said optimizing mode of operation when said output string voltage is less than said transition voltage value.
 16. A plurality of said solar photovoltaic electrical power generators of claim 8 interconnected to one another, wherein said plurality of said power optimizer output positive and negative electrical leads are connected in electrical series. 